ACTA ENDOCRINOLOGICA (BUC)

Introduction. The expression of menin in the thyroid gland has long been debated. Animal models with targeted inactivation of menin in the thyroid gland have shown that its inactivation might play a role in the progression to a more aggressive type of cancer. Human studies are conflicting, some have identified mutations in the MEN1 gene in a subtype of oncocytic thyroid carcinomas, while others have not identified a higher prevalence of thyroid cancer in MEN1 patients. Objective. To analyze the immunohistochemical expression of menin in different types of thyroid carcinomas. Materials and methods. 48 thyroid tumours (12 papillary thyroid carcinomas (PTC), 6 anaplastic thyroid carcinomas (ATC), 12 poorly differentiated thyroid carcinomas (PDTC), 5 medullary thyroid carcinomas (MTC), 5 oncocytic follicular carcinomas (OC), 3 oncocytic adenomas (OA) and 5 goiters (G)) were tested for nuclear expression of menin using an anti-menin antibody. The expression was considered positive, negative or decreased. Results. The expression of menin was positive, identical to normal tissue, in 39 cases (81.25%). The expression was decreased (n=8) or absent (n=1) in 9 tumours (18.75% - 2 PTC, 5 PDTC, 2 OC) accounting for 42% (5/12) of the PDTC and 40% (2/5) of the OC. Conclusions. Our results show that the expression of menin is generally preserved in human thyroid carcinomas, but it can be decreased or absent in certain types of thyroid cancer. Further molecular studies are needed to evaluate to potential of menin protein in tumorigenesis.

Intracranial germ cell tumors (GCT) are rare brain tumors that typically arise in the pineal or suprasellar regions. Germinomas are highly radiosensitive among pediatric CNS tumors. Suprasellar GCTs most commonly present with hypothalamic/ pituitary dysfunctions. We report a case of an 18 year old boy with particularly long term evolution from the onset of symptoms to the positive diagnosis of suprasellar germinoma. At 9 years he was diagnosed with idiopathic central diabetes insipidus and started DDAVP therapy. In the subsequent years he presented delay in longitudinal growth and delayed pubertal development. At 16 years he was referred to our institute with relatively good general condition despite an extremely severe hypernatremia of 186 mEq/L, serum osmolality of 405 mOsm/kg and impaired thirst sensation. He developed sinus thrombosis as a consequence of hyperosmolality and presented intermittent rises of temperature, but no septic episodes. During a long term follow neuroimaging eventually revealed a thickening of the pituitary stalk, mimicking as an infiltrative lesion. Finally, two supracentimetric tumor nodules were shown on contrast enhanced MRI in the suprasellar region and at the floor of the left lateral ventricle. Stereotactic biopsy concluded a pure germinoma, and craniospinal irradiation was performed. At present he has an infracentimetric suprasellar tumor remnant, reperfused sinus veins, optochiasmatic syndrome sequelae. He benefits from L-Thyroxin and testosterone replacement, and maintains hydro-electrolytic balance on DDAVP and controlled oral fluid intake.

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